Option: Allow direct access to the underlying value via operator->

Crashes if the Option is empty.

libluna/include/luna/Option.h

@@ -109,6 +109,13 @@ template <typename T> class Option
         return true;
     }
 
+    // NOTE: This should also exist in Result.
+    T* operator->()
+    {
+        expect(has_value(), "Option::operator-> called on an empty Option");
+        return &m_storage.fetch_reference();
+    }
+
     ~Option()
     {
         if (has_value()) m_storage.destroy();